Means and method of cementing tungsten carbide to other metals



Ma;y 24, 1932. w c pm I 1,860,275

MEANS AND METHOD OF CEMENTING TUNGSTEN CARBIDE TO OTHER METALS FiledNov. 16, 1929 gwvmtoz Patented May 24, 1932 UNITED STATES.

PATENT OFFICE WILLIAM R. CHAIIN, OF INDIANAPOLIS, INDIANA.

MEANS AND METHOD CEMENTING TUNGSTEN CARBIDE TO OTHER METALS Applicationfiled November 18, 1929. Serial No. 407,741.

This invention relates to methods of cementing o'r brazing tungstencarbide and similar materials to a steel shank or base to be used inmaking various kinds of cutt ng tools, punches, dies, etc.

Heretofore it has been generally believed that tungsten carbide couldnot be heated to temperatures in excess of 2000 degrees l3.

without serious injury to the tungsten carbide 1c and furthermore thatjoining tungsten carbide to a steel base of a shank required expensiveand special equipment and that the work must be done in anatmosphere ofgas which would not affect the tungsten carbide. This belief limited themaking of carbide tools to only a few skilled persons familiar with adelicate process and prohibited its use except with expensive apparatus.I have discovered that tungsten carbide tools can 7 2: be cemented to asteel base or shankby a rocess which is simple and easily practiced yany one skilled in this art.

Referring to the 'accompanyin drawing which is made a part hereofthegure indicates a machine tool shank or base showing a hardened cuttingblock of tungsten carbide or other hard metal cemented to the'base. Inthe drawing numeral 10 indicates; a shank of steel having a socket cutout at 11 at to receive a cutting block 12 of suitable hard metal suchas tungsten carbide. In carr 'ng .out my process I place in the-bottom othe recess 11 a special cement-which is spread to about of an inch indepth and the tungsten carbide bit 12 which has been polished clean isplaced in the recess on the top of the coment. A liberal quantity of drypowdered boric acid or some of its derivatives, such as I borax or boraxglass is'sprinkled all over the I top of the bit and completely fillingthe crevices in the shank around the bit. The tool is 4 then placed in asuitable tool heat treating furnace which is maintained at sufiicientlow dently. The tool is then transferred to another ordinary-heattreating furnace and the tool heated to a temperature sufiicienttothoroughlymelt the cementing medium; If the cement is any of thosecompounds cov- 53 ered by my prior Patents No. 1,699,346-or temperatureso as not to heat the bit too sud- 1,362,472 the temperature should beabout 2200 to 2350 degrees F. If copper or its compounds are used as ajoining medium the temperature need not exceed 2000 degrees F. Sinceboric acid and its compounds mentioned above melt at a relatively lowtemperature and become fluid the entire surface of the bit and the jointitself is completely sealed from the gases of the furnace during theheating. When the tool is brought up to the proper high temperature it"is taken from the furnace and the excess o'f the cementing medium is atonce squeezed out with a suitable means such as a press vice, etc

If carried out as described in my previous patents this squeezingoperation would unduly chill the tungsten carbide bit and cause it tocrack. To avoid this danger I place between the bit and the pressv pieceof steel of suflicient thickness which is heated to apgroximately thesame temperature as the bit. y doing t is thesqueezing operation abovementioned can be carried out without chilling the bit. The pressure ismaintained for a short time so as to allow the cementing medium to setand then the tool is laced at ble to cement tungsten carbide to 'a steelshank with the ordinary heat treating equip- -ment now in universal use.

7 It will be obvious to those skilled inthe art that variousc'hanges maybe made in' my device without departing from the spirit of the inventionand therefore I do not limit myself to what is shown in the drawing anddescribed in the specification, but only as indicated in the appendedclaims.

Faving thus ully described my, said invention, what I claim as new anddesire to secure by Letters Patent, is:

1. The method of cementing a tungsten carbide block to a base whichcomprises ap plying a cementing compound to the base, pressing thetungsten carbide block thereto, covering the block and the base with aquantity of boric acid, subjecting the whole to a temperature sufficientto melt the boric acid to provide a coating to insulate the block andthe base from injurious gases in the furnaces, and then heating theassembled base and block to a temperature suflicient to melt thecementing compound, and removing the shank and tool and subjecting thecementing compound to a pressure while it cools, substantially as setforth.

2. The method of cementing a tungsten carbide block to a base whichcomprises applying a cementing compound to the base, pressing thetungsten carbide block thereto,

coverin the block and the base with a quan-'- tity of oric acid,subjecting the whole to a temperature suflicient to melt the boric acid,and then heating the assembled base and block to a temperaturesuflicient to melt the cementing compound, removing the shank and tooland subjecting the cementing compound to a pressure while it cools, andj acketing the assembled unitto prevent rapid cooling, substantially asset forth. 3. The method of cementing a high speed cutting tool to abase which comprises applying a cementing compound to the base, applyingthe tool thereto, covering the base and the tool with a boric acidderivative, applying a temperature suflicient to melt the boric acidderivative to coat the tool and the base,

tive', subjecting the block to-a temperature suflicient to melt theboric acid derivative, then subjecting the block and the base in aclosed chamber to a temperature suficient to melt the cementingcompound, then placing the base and the block in a device whereby theymay be pressed together and covering the whole with a powder to allowthem ing, the base and the block in a device where by they may bepressed together and covering the whole with a powder to allow them tocool slowly, and insulating the block and the base against contact withthe pressing means to prevent a sudden cooling of the block,substantially as set forth.

In witness whereof, I have hereunto set my hand at Indianapolis,Indiana, this 14th day of November, D. nineteen hundred and twenty-nine.

WILLIAM R. CHAPIN.

and subjectin the whole assembly to a temperature sufficient to meltthecementing compound, and sub'ecting the tool and base to a pressure tohol them tight together during the cooling of the cement, substantiallyas set forth.

,4. The method of cementing a high speed cutting tool to a base whichcomprises applying a cementing compound to the base, applying the toolthereto, covering the base and the tool with a boric acid derivative, aplying'a temperature sufiicient to melt the lioric acid derivative tocoat the tool and the base, subjecting the wholev assembly to atemperature suiiicient to melt the cementing compound, subjecting thetool and base to apressure to hold them'tight-to ther during the coolingof thecement, an applying an insulating powder about the tool and thebase to prevent too rapid cooling, substantially as set forth.- i

5. The method of ceinenting a block of hollowing out the base to iit thesaid block applying cementing compound to the said hollow, placing theblock in, the hollow and covering the same with a boric acid derive-

